Lead-antimony alloy for battery plate grids



United States Patent 2,993,785 LEAD-ANTIMONY ALLOY FOR BATTERY PLATE GRIDS Heinz Borchers, Mnnieh, Dietrich Evers, Hagen, Westphalia, and Herbert Gurnpreeht, Ennepetal-"Milspe, Germany, assignors to Accnmnlatoren-Fabriir Aktiengesellschait, Hagen, Westphalia, Germany No Drawing. Filed Feb. 25, 1960, Ser. No. 10,872 Claims priority, application Germany Mar. 11, 19:9 6 Claims. (Cl. 75-166) The invention relates to lead-antimony alloys for use in electric storage battery plate grids and, more particularly, to such alloys containing a minimum amount of arsenic while exhibiting unusually strong resistance to corrosion.

A lead-antimony alloy for the same purpose formerly has been disclosed containing to 11 percent, and preferably 5 to 8 percent, antimony, 0.075 to 0.1 percent arsenic, 0.04 to 0.12 percent copper, and lead as the balance. That alloy displays a particularly high corrosion resistance as compared to the customary hard-lead alloys, simultaneously exhibiting sufileient hardness and physical strength. It has been proven that this alloy, when used in electric storage batteries, especially as positive plates, leads to a considerably higher discharge value of the batteries than attained with the grids made of conventional alloys.

However, in certain areas of application an arsenic content of even as low as 0.075 percent potentially leads to the formation of arsenic hydride when the battery emits gas. As is well known, arsenic hydride is highly poisonous aflecting the health ofhuman beings in very small quantities and may even have fatal effects. Whereas in many instances batteriw are located in rooms having suificient air circulation that fatal or noxious concentrations of arsenic hydride do not occur, certain special applications allow the concentration of arsenic hydride. This may occur in such confined spaces as in submarine batter-y rooms or with stationary batteries being constantly on a trickle charge, such as telephone batteries, which also are in closed spaces so that a concentration of arsenic hydride may take place.

It has been established that an addition of as little as 0.04 to 0.12 percent copper to the binary hard lead alloy considerably increases the corrosion resistance. However, this effect is not uniform. Surprisingly, it now has been found that the addition of very small amounts of arsenic, i.e., 0.01 to less than 0.075 percent, and prefer-ably 0.03 to '0.07 percent, assures the stabilizing eifect of the copper addition in all instances so that an arsenic addition of 0.075 percent or more is not required.

According to the invention, hence, the alloy for battery plates exposed to constant trickle charges and for batteries disposed in non-ventilated areas contains 5 to '11 percent, and preferably 5 to 8 percent, antimony, 0.01 to less than 0.075 percent arsenic, 0.04 to 0.12 percent copper, and, as the balance, lead.

The effect obtained according to the invention, which is the inhibition or at least reduction below harmful levels of the formation of arsenic'hydride while maintaining an uncommonly high corrosion resistance, also is obtained when the alloy contains the customary impurities, such as small quantities of silver, bismuth, or other metals.

When an even more increased corrosion resistance is desired, 0.01 to 1 percent silver can be added to the alloy, and a corrosion resistance not heretofore attained is experienced.

Depending upon the end use, with the addition of silver, the copper content can be decreased. For instance, when a very high silver content, e.g., 1 percent has been selected, an especially small amount of copper may be "ice Percent Antimony 5-11 Arsenic 0.01-less than 0.075 Copper 0.04-0.12 Lead Balance 2. A lead-antimony alloy for grids of electric storage battery plates having high corrosion resistance, comprising Percent Antimony 5-8 Arsenic 0.03-0.07 Copper 0.04-0.12 Lead Balance 3. A lead-antimony alloy for grids of electric storage battery plates having high corrosion resistance, comprising Percent Antimony 5-11 Arsenic 0.01-less than 0.075 Copper 0.04-0.12 Silver 0.01-1.0 Lead Balance 4. A lead-antimony alloy for grids of electric storage battery plates having high corrosion resistance, comprising Percent Antimony 5-1 1 Arsenic 0.01-less than 0.075 Copper 0.03-0.05 Silver 1 Lead Balance 5. A lead-antimony alloy for grids of electric storage battery plates having high corrosion resistance, comprising Percent Antimony 5-11 Arsenic 0.01-less than 0.075 Copper 0.09-0.12 Silver 0.01 Lead Balance 6. A lead-antimony alloy for grids of electric storage battery plates having high corrosion resistance, compriss References Cited in the file of this patent FOREIGN PATENTS Great Britain Apr. 27, 1955 Canada June 18, 1957 OTHER REFERENCES Metals Handbook, 1948 edition, American Society for Metals, page 952, 

1. A LEAD-ANTIMONY ALLOY FOR GRIDS OF ELECTRIC STORAGE BATTERY PLATES HAVING HIGH CORROSION RESISTANCE, COMPRISING 